Along with the widespread of 3C (Computer, Communication, Consumer electronics) products and consumable electronic products (for example, smart phone, tablet PC (personal computer), and motion-sensing game console) in recent years, the market demand for microelectronic inertial devices (for example, accelerometer and gyroscope) has been exploding. The design of gyroscope is going towards digital output and high precision. Thus, many international manufacturers devote considerable resources to the development of new generation digital inertial sensors with high performance-price ratio. In particular, because the accelerometer techniques have relatively matured, the performance-price ratio of digital angular-rate sensors will determine the competitiveness of the digital inertial sensors in the inertial device market.
A Coriolis accelerometer in a conventional gyroscope outputs two signals: an angular-rate signal and a resonance signal which has the same oscillation frequency but different phase as a resonator. Thus, the resonance signal needs to be removed from the output of the Coriolis accelerometer through demodulation to obtain the angular-rate signal. If a stray capacitance and inductance effect occurs between the Coriolis accelerometer and the resonator, a coupling influence is received by the output signal of the Coriolis accelerometer from the resonance signal, so that an error occurs on an output terminal of the gyroscope. Because the output signal of the resonator and the output signal of the Coriolis accelerometer have almost the same frequency, the resonance signal cannot be filtered out by using a filter in a reading circuit. However, the interference produced by the resonance signal is a major factor in the reduction of the output accuracy of the gyroscope, and whether the gyroscope can provide an accurate angular rate measurement is determined by whether the resonance signal can be removed. Thereby, the signal output by any conventional Coriolis accelerometer comes with the interference of a resonance signal.